I mean its my bread and butter but I do also have a slight agreement. There is no exact science to it. Those with big budgets are either adding to their already established brand OR trying to enter the market, as many of those entering the market spending big fail as companies as they do succeed which tells its own story about how powerful marketing is and in some cases isn't. Getir went massively big on consumer marketing spend and went under others will write off the value because they are so big its impossible but also not crucial to track. I doubt many sponsors can track the increase from sports sponsorship unless there is a call to action to buy with a code and then you can. Many will attribute natural growth to the marketing but its almost impossible to know for sure.
I did a sponsorship deal with a golfer many moons back and the value was calculated how many times he was seen on TV during the majors the year before when he came 4th in the Masters, so the deal was hefty, we did the deal at less but still a fair chunk of change. That deal was more about us being able to say we sponsor him and use him to hosts clients that liked golf on a specific day in the year than it was the idea people were picking up the phone whilst watching the golf and buying our hotel rooms.
Most of it is ego chasing, host your clients in the box which is included in the deal and see your name all round for the day, deals done in the box more than consumers really linking the two and buying the product is where the value does sit, even then I don't think its to the same number spent on the sponsorship IMO
